< p>TUCSON, Ariz. (AP) — A University of Arizona researcher indicates that a lot of the helium balloons released in Tucson end up in Saguaro National Park sections that flank the southern Arizona city.

Doctoral student Erin Zylstra's computer modeling found that a square kilometer in the park's Rincon unit east of Tucson had 62 shriveled latex balloons hanging on trees, melting on rocks or just generally strewn about

According to the Arizona Daily Star (http://bit.ly/XT2Tks ), that's more than the 30 tortoises, 26 rattlesnakes and 29 plastic bags per square kilometer that Zylstra's peer-reviewed research found.

Zylstra says wind patterns blow balloons into the park, where they pose potential threats if they're eaten by animals or entangle them.

National Park Service biologist Don Swann says Zylstra's research shows how people's decisions can affect wilderness areas.